Erythrocyte zinc and serum copper in male and female adolescents according to puberty stage at different growth phases

BACKGROUND: Considering that modification in body composition and growth velocity leads to alterations in zinc and copper nutritional status, the purpose of the study was to assess erythrocyte zinc and serum copper in adolescents of both genders, according to the stage of sexual maturity at different growth phases. METHODS: Two hundred and eighty-six adolescents were assessed, 157 were female, with body mass index Z-scorebetween−2 and +2. Clinical biochemical measurements were assessed using atomic absorption spectrophotometry. Student's t, Kruskal-Wallis, and Bonferroni tests were used. RESULTS Median serum copper was superior, and zinc was inferior to respective reference values in all groups. Serum copper presented significant reduction in the final stages of pubertal development in males; in turn, erythrocyte zinc values increased linearly with the evolution of puberty stages in both genders. Comparison between genders in each stage of growth showed significant difference in peak acceleration and in deceleration for erythrocyte zinc and serum copper, with both being higher in females. CONCLUSIONS: Serum copper is inversely influenced by modifications that occur with the evolution of puberty in males, whereas erythrocyte zinc is directly influenced in both genders, although always with deficient deposition. At peak acceleration and deceleration of growth, there is greater mobilization of erythrocyte zinc and serum copper in males, when compared with females, which does not occur at the onset of the acceleration of growth.

Leptin and adiponectin in the female life course

Adipose tissue secretes a variety of adipokines, including leptin and adiponectin, which are involved in endocrine processes regulating glucose and fatty metabolism, energy expenditure, inflammatory response, immunity, cardiovascular function, and reproduction. The present article describes the fluctuations in circulating leptin and adiponectin as well as their patterns of secretion in women from birth to menopause. During pregnancy, leptin and adiponectin seem to act in an autocrine/paracrine fashion in the placenta and adipose tissue, playing a role in the maternal-fetal interface and contributing to glucose metabolism and fetal development. In newborns, adiponectin levels are two to three times higher than in adults. Full-term newborns have significantly higher leptin and adiponectin levels than preterms, whereas small-for-gestational-age infants have lower levels of these adipokines than adequate-for-gestational-age newborns. However, with weight gain, leptin concentrations increase significantly. Children between 5 and 8 years of age experience an increase in leptin and a decrease in adiponectin regardless of body mass index, with a reversal of the newborn pattern for adiponectin: plasma adiponectin levels at age five are inversely correlated with percentage of body fat. In puberty, leptin plays a role in the regulation of menstrual cycles. In adults, it has been suggested that obese individuals exhibit both leptin resistance and decreased serum adiponectin levels. In conclusion, a progressive increase in adiposity throughout life seems to influence the relationship between leptin and adiponectin in women.

Association of Serum Retinol Binding Protein 4 with Adiposity and Pubertal Development in Korean Children and Adolescents

Retinol binding protein 4 (RBP4) has been postulated to provide a new link between obesity and insulin resistance. We aimed to assess the relationship between serum RBP4 and insulin resistance by investigating serum RBP4 levels in children and adolescents according to degree of obesity and pubertal stage. A total of 103 (30 lean, 39 overweight, 34 obese) were evaluated for serum RBP4, adiponectin, insulin, glucose and lipid profiles. RBP4 levels of obese and overweight groups were higher than those of lean group. RBP4 level was higher in pubertal group than in prepubertal group. RBP4 was positively correlated with age, height, weight, body mass index (BMI), abdominal circumference, systolic blood pressure, fasting insulin, homeostatic model assessment of insulin resistance (HOMA-IR), total cholesterol and triglyceride, and inversely with adiponectin. In the multiple linear regression analysis, RBP4 was found to be independently associated with pubertal stage, BMI and triglyceride but not with HOMA-IR. In conclusion, serum RBP4 level is related with degree of adiposity and pubertal development. The association of RBP4 with insulin resistance is supposed to be secondary to the relation between RBP4 and adipose tissue in children and adolescents.

A Higher Burden of Small Low-density Lipoprotein Particles is Associated with Profound Changes in the Free Androgen Index in Male Adolescents

From a young age, males are at higher cardiovascular risk than females. Dyslipidemia, including a higher burden related to small low-density lipoproteins (LDL), plays an important role in precipitating atherosclerosis in both males and females. We investigated sex differences in atherogenic lipoprotein burden and the independent predictors of LDL particle size in children and adolescents. We measured the concentrations of total testosterone, sex hormone-binding globulin, estradiol, total cholesterol, triglyceride, LDL cholesterol, HDL cholesterol, and LDL particle size in 135 children and adolescents (67 boys, 68 girls). The free androgen index was significantly and negatively correlated with LDL particle size (r = -0.273, P = 0.026) in boys, but estrogen and LDL particle size were not related. In a stepwise multiple regression analysis adjusted for body mass index, age, and homeostasis model assessment for insulin resistance, free androgen index was still an independent predictor of LDL particle size in boys (R2 = 0.075, P = 0.026). The prominent decrease in LDL particle size along with increased testosterone concentrations in males might explain why they are more likely to display atherogenic dyslipidemia from adolescence.

Sex hormone binding globulin decrease as potential pathogenetic factor for hirsutism in adolescent girls / Disminución de la globulina transportadora de hormonas sexuales como factor patogénico de hirsutismo en la adolescencia

We investigated 252 non-obese female subjects aged 13-39 years to evaluate if an exaggerated descent of sex hormone binding globulin (SHBG) levels during adolescence can play a role in the development of hirsutism. Body hair was assessed according to Ferriman and Gallwey (FG), with a stringent criterion of normality of < 4. In 13-14 years girls, SHBG and free testosterone (FT) levels were similar in "hirsute" girls (FG > 4) and controls (FG < 4, regular menstrual cycles, no acne). In 15-18 years girls, SHBG values were lower in "hirsute" girls, FT levels were similar in both groups, FG correlated inversely with SHBG. In 19-39 yr women, FT levels were higher in "hirsute" subjects, SHBG values were similar in both groups, FG correlated positively with FT. Lowest SHBG values were observed at 15-18 years, but the slope of the decrease from 1314 years values was greater in the "hirsute" group. FT values increased progressively with age, but the increase was greater in the "hirsute" group. Those results suggest an important role of SHBG decrease in adolescence vs. a more accentuated testosterone increase in adults, as factors conditioning the development of hirsutism in these two different periods of life.

Se investigaron 252 mujeres con peso normal, de 13 a 39 años de edad, para evaluar si un descenso exagerado en los niveles de la globulina transportadora de hormonas sexuales ("sex hormone binding globulin"; SHBG) puede tener un rol en el desarrollo de hirsutismo. Este signo fue evaluado con la escala de Ferriman y Gallwey (FG), empleando un criterio riguroso de normalidad < 4. En niñas de 13-14 años, tanto SHBG como la testosterona libre ("free testosterone"; FT) fueron similares en niñas "hirsutas" (FG > 4) y controles (FG < 4, ciclos menstruales regulares, sin acné). En adolescentes de 15-18 años, los valores de SHBG fueron menores en las "hirsutas", los niveles de FT fueron similares en ambos grupos y el índice de FG correlacionó inversamente con SHBG. En las mujeres de 19-39 años, los niveles de FT fueron mayores en las "hirsutas", los valores de SHBG fueron similares en ambos grupos y FG correlacionó positivamente con FT. Los valores más bajos de SHBG se observaron entre 15 y 18 años, pero la pendiente de disminución a partir de los valores de 13-14 años fue mayor en el grupo de "hirsutas". Los valores de FT se incrementaron progresivamente con la edad, pero el aumento fue mayor en el grupo de "hirsutas". Estos resultados sugieren un rol importante del descenso de SHBG en la adolescencia vs. un incremento más acentuado de los niveles de testosterona en las adultas, como factores que condicionan el desarrollo del hirsutismo en esos dos diferentes periodos de la vida.

Sensibilidad insulínica en niños de 6 a 15 años: asociación con estado nutricional y pubertad / Insulin sensitivity in children aged 6 to 16 years: Association with nutritional status and pubertal development

Backgrounds: There is a high prevalence of obesity and hyperinsulinism among Chilean prepuberal children. Aim: To evaluate insulin sensitivity (IS) using fasting insulin, the Homeostasis Model Assessment (HOMA) and quantitative insulin-sensitivity check index (QUICKI) in Chilean children. Material and Methods: Body mass index (BMI), total body fat percentage ( percentTBF) using the sum of 4 skin folds, abdominal obesity determined through waist circumference (WC), pubertal maturation using five Tanner stages, fasting glucose (Glu) and insulin (Ins), were measured in 354 children aged 6 to 15 years (173 males). IS was evaluated using HOMA and QUICKI. Results: IS was strongly associated with percentTBF and WC. Ins, HOMA and QUICKI were significantly correlated with BMI (r =0.412; 0.405 y -0.442, respectively), percentTBF (r =0.370; 0.367 y -0.394, respectively), and WC (r =0.452; 0.446 y -0.481, respectively). Ins and HOMA increased and QUICKI decreased significantly (p <0.0001) with age. Children in a similar Tanner stage did not have differences in Ins, HOMA and QUICKI. No differences in Ins, HOMA and QUICKI were observed between children in Tanner stages 1 and 2. However, children in Tanner stages 1 and 2, had significantly lower Ins and HOMA and higher QUICKI than those in Tanner 3 to 5 stages. The highest Ins quartile for Tanner stages 1 and 2 was 10.0 æUI/dl; for Tanner stages 3 to five, the figure was 15.6 æUI/dl. Conclusions: These results confirm the relationship of IS with BMI, percentTBF, WC and pubertal maturation. IS decreases significantly and fasting Ins levels increase approximately 50 percent with puberty. This fact must be considered for the diagnosis of hyperinsulinism and insulin resistance in children.

Níveis séricos de hemoglobina em adolescentes segundo estágio de maturação sexual / Hemoglobin serum levels in adolescents according to sexual maturation stage

A adolescência constitui etapa de risco para o desenvolvimento da anemia ferropriva, uma vez que ocorre aumento da necessidade de ferro decorrente do crescimento estatural e da maturação biológica. Estudaram-se 130 adolescentes, de ambos os sexos, para verificar os valores de hemoglobina sérica em diferentes fases de maturação sexual. Utilizou-se o método de fotometria para dosar a hemoglobina sérica e realizou-se auto-avaliação do estágio de maturação sexual com base nos critérios de Tanner. Os níveis médios de hemoglobina foram semelhantes entre sexos, bem como entre meninas que menstruavam ou não. O nível médio de hemoglobina foi de 13,3g/dL tanto para os meninos como para as meninas (p=0,64), com desvios-padrão de 1,12 e de 0,83, respectivamente. Entre os adolescentes estudados, 7,7 por cento tinham anemia ferropriva. Recomenda-se atenção ao grupo de adolescentes, devido ao aumento da necessidade de ferro durante o estirão de crescimento, principalmente entre as meninas, aumentando a suscetibilidade à anemia.

Effects of testosterone on growth hormone secretion and somatomedin-C generation in prepubertal growth hormone deficient male patients

1. The role of testosterone (T) in growth was evaluated in 11 prepubertal hypopituitary males during two 15-day periods separated by a 4-week interval, i.e., before (PRE-T period) and during T ester treatment (50 mg every 5 days, 3 im doses-T period). 2. T increased growth hormone (GH) secretion, assessed by 4-h rhythm (mean +/- SEM = 1.90 +/- 0.27 vs 1.77 +/- 0.21 ng/ml; P < 0.05) and after a GHRH stimulus (3.42 +/- 0.54 vs 3.08 +/- 0.43 ng/ml; P < 0.05) as compared to the PRE-T period. 3. T also increased basal somatomedin-C (SM-C) levels (0.20 +/- 0.03 vs 0.15 +/- 0.02 U/ml; P < 0.001) and SM-C generation. After GH was administered in 4 im doses (0.01, 0.02, 0.05 and 0.1 U/kg), SM-C levels were 0.31 +/- 0.08 vs 0.24 +/- 0.07 U/ml, P < 0.001. T did not change incremental (absolute minus basal) SM-C levels (0.15 +/- 0.08 vs 0.12 +/- 0.07 U/ml; P > 0.05). 4. The results suggest that T increased plasma SM-C levels by stimulating residual GH secretion in hypopituitary males

Colesterol y triglicéridos sanguíneos en adolescentes durante el desarrollo sexual / Blood cholesterol and triglycerides in adolescents during sexual development

Se midieron las concentraciones séricas de colesterol y triglicéridos en 152 adolescentes (53 varones y 99 mujeres) que acudieron a control de salud al Consultorio Integral de Adolescentes Valparaíso. Las concentraciones de colesterol total fluctuaron entre 120 mg/dl (percentil 10) y 220 mg/dl (percentil 90) y 20,4%estaban sobre 200 mg/dl. Las de triglicéridos fluctuaron entre 57 mg/dl (percentil 10) y 161 mg/dl (percentil 90) siendo 11,9%mayores que 150 mg/dl. Sólo se encontró una tendencia a la asociación entre concentraciones de colesterol total y desarrollo mamario, en cambio se encontró asociación clara entre colesterol e índice de masa corporal (p < 0,01) y antecedente familiar de enfermedad coronaria (p < 0,02)

Serum gonadotropins and estradiol levels in Turkish pubertal girls.

Serum follicle stimulating hormone (FSH), luteinizing hormone (LH) and estradiol (E2) levels were measured by radioimmunoassay in the sera of 37 healthy Turkish pubertal girls. The data show that FSH levels significantly increased from stage 2 to 3, and tented to plateau during stages 3,4 and 5, and LH and estradiol levels constantly rises with advances in sexual development and significantly correlates with pubertal stages. When the serum FSH level was compared in pre and postmenarcheal girls of the same age the level was almost identical. Adversely, LH and estradiol levels were higher in postmenarcheal girls than in premenarcheal girls.